package demo1;

public class MyLinkedList {
    static class ListNode{
        public int val;
        public ListNode prev;
        public ListNode next;

        public ListNode(int val) {
            this.val = val;
        }
    }
    public ListNode head;
    public ListNode last;

    //得到链表的长度
    public int size(){
        int count = 0;
        ListNode cur = head;
        while (cur != null){
            cur = cur.next;
            count++;
        }
        return count;
    }


    //打印
    public void display(){
        ListNode cur = head;
        while (cur != null){
            System.out.println(cur.val +" ");
            cur = cur.next;
        }
        System.out.println();
    }

    //查找是否包含关键字key是否在链表当中
    public boolean contains(int key){
        ListNode cur = head;
        while (cur != null){
            if (cur.val == key){
                return true;
            }
            cur = cur.next;
        }
        return false;
    }


    //头插法
    public void addFirst(int data){
        ListNode node = new ListNode(data);
        if (head == null){
            head = node;
            last = node;
            return;//插入完成，return
        }
        node.next = head;
        head.prev = node;
        head = node;

    }


    //尾插法
    public void addLast(int data){
        ListNode node = new ListNode(data);
        if (head == null){
            head = node;
            last = node;
        }else {
            last.next = node;
            node.prev = last;
            last = node;
        }
    }

    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data){
        int size = size();
        if (index<0 || index>size){
            throw new IndexOutOfBounds("引用不合法");
        }
        if (index == 0){
            addFirst(data);
            return;
        }
        if (index == size){
            addLast(data);
            return;
        }
        ListNode cur = head;
        while (index != 0){
            cur = cur.next;
            index--;
        }
        ListNode node = new ListNode(data);
        node.next = cur;
        cur.prev.next = node;
        node .prev = cur.prev;
        cur.prev = node;
    }

    //删除第一次出现关键字为key的节点
    public void remove(int key){
        ListNode cur = head;
        while (cur != null){
            if (cur.val == key){
                //开始删
                if (cur == head){
                    //删除头节点
                    head = head.next;
                    //只有一个节点的时候
                    if (head != null){
                        head.prev = null;
                    }
                }else {
                    cur.prev.next = cur.next;
                    if (cur.next != null){
                        //cur.prev.next = cur.next;
                        cur.next.prev = cur.prev;
                    }else{
                        //删除尾巴节点
                        //cur.prev.next = null;//cur.prev.next = cur.next
                        last = last.prev;
                    }
                }
                return;
            }else {
                cur = cur.next;
            }
        }
    }

    //删除所有值为key的节点
    public void removeAllKey(int key){
        ListNode cur = head;
        while (cur != null){
            if (cur.val == key){
                //开始删
                if (cur == head){
                    //删除头节点
                    head = head.next;
                    //只有一个节点的时候
                    if (head != null){
                        head.prev = null;
                    }else {
                        last = null;
                    }
                }else {
                    cur.prev.next = cur.next;
                    if (cur.next != null){
                        //cur.prev.next = cur.next;
                        cur.next.prev = cur.prev;
                    }else{
                        //删除尾巴节点
                        //cur.prev.next = null;//cur.prev.next = cur.next
                        last = last.prev;
                    }
                }
                /*cur = cur.next;*/
            }/*else {
                    cur = cur.next;
                }*/
            cur =cur.next;//继续寻找
        }
    }

    //清空列表
    public void clear(){
        ListNode cur = head;
        while (cur != null){
            ListNode curNext = cur.next;
            cur.prev = null;
            cur.next = null;
            cur = curNext;
        }
        //头和尾也得释放
        head = null;
        last = null;
    }

}
